The present disclosure relates generally to integrated circuits, and more particularly to an apparatus and method for improving accuracy of a linear voltage regulator (LVR).
An adjustable shunt regulator (ASR) is a well known integrated circuit (IC) chip that provides a regulated output voltage that is used as a highly accurate, programmable reference source. The ASR is often included in the design of a power supply system. A linearly acting semiconductor device such as a linear voltage regulator (LVR), operating in shunt with a source or load, is also used as a basic building block of a power supply that provides power to electronic devices. The output voltage of the LVR is linearly adjustable between a minimum voltage level, e.g., 2.5 volts, and a maximum voltage level, e.g., 36 volts, by selecting appropriate values of external resistors used in conjunction with the ASR. The ASR typically provides specified accuracy over a specified operating temperature range. Examples of commercially available ASR products include low-voltage adjustable precision shunt regulators TLV1431 and TLV431A manufactured by Texas Instruments Incorporated, Dallas, Tex.
Accuracy of the output voltage provided by the ASR is typically valid at a fixed value of a cathode current, as stated in the ASR product specification data sheet. However, the accuracy often deteriorates rapidly as the cathode current deviates from the fixed value. Therefore, a need exists to provide a method and apparatus for providing a regulated, linear voltage output having an improved accuracy.